1. Field of the Invention
The invention relates to a method and a device for installing digital or analogue broadcasting channels.
More particularly, the invention relates to the field of audio and/or video receiving systems. It especially relates to systems complying with the DVB (acronym for “Digital Video Broadcast”) standard. It also relates to analogue receiving systems.
2. Description of Related Art
The installation of a digital decoder requires searching all the available channels that it is desired to install within a given frequency band.
Each channel is centred on a frequency which the demodulator of the installation device tries to capture when installing various channels. However, this central frequency transmitted by the programme broadcaster is subject to variations and is not exactly the frequency received. The variations in frequency are due to various factors and especially to the following factors:                the accuracy of the transmitter, which alters the frequency transmitted with respect to its ideal frequency,        the drifts of the various components which alter the frequency received.        
When the frequency received is subject to these variations, the demodulator attempts to capture the frequency and risks being unsuccessful, which means that the channel is not installed.
Known devices make it possible to detect the channel even if the frequency is subject to variations. Such devices lock on to the central frequency and attempt to capture it. If they are not successful, that is to say if there was drift, they try to capture the frequencies below the nominal frequency and the frequencies above this nominal frequency within a frequency span centred on the nominal frequency span of the channel and called pick-up or capture span, the length of which is a function of the demodulation component.
However, these devices make the installation very lengthy, which is particularly undesirable for the user who wishes to install a new set of programmes.